It's
summer. For many of us, summer is a time synonymous with fresh corn,
one of the major field crops produced in the United States.

In
2011, corn was planted on more than 92 million acres in the U.S.,
helping the nation continue its trend as the world's largest exporter of
the crop.

Corn
is a nitrogen-loving plant. To achieve desired production levels, most
U.S. farmers apply synthetic nitrogen fertilizer to their fields every
year.

Once
nitrogen fertilizer hits the ground, however, it's hard to contain and
is easily lost to groundwater, rivers, oceans and the atmosphere.

"That's
not good for the crops, the farmers or the environment," says Phil
Robertson, a scientist at Michigan State University and principal
investigator at the National Science Foundation's (NSF) Kellogg
Biological Station (KBS) Long-Term Ecological Research (LTER) site.

KBS is one of 26 such NSF LTER sites across the United States and around the globe in ecosystems from forests to coral reefs.

Nitrogen
lost to the environment from agricultural fields is nitrogen not used
by crops, Robertson says. "This costs farmers money and degrades water
and air quality, with significant health, biodiversity and downstream
economic effects."

Farmers
already manage fertilizer to avoid large losses. But, to reduce losses
further, it currently costs more money than the fertilizer saves.

Robertson
and colleagues are working on a way to help make the time and expense
of efforts to mitigate fertilizer loss worthwhile. They're putting the
finishing touches on a program that would pay farmers to apply less
nitrogen fertilizer in a way that doesn't jeopardize yields. The
program, called the nitrous oxide greenhouse gas reduction methodology,
is being conducted in partnership with the Electric Power Research
Institute.

"This
project is a great example of how long-term, fundamental research can
contribute practical solutions to important environmental problems of
concern in the U.S.—and ultimately around the world," says Matt Kane, an
NSF program director for LTER.

In
the United States, agriculture accounts for almost 70 percent of all
nitrous oxide emissions linked with human activity. Nitrous oxide is one
of the major gases contributing to human-induced climate change; it has
a lifetime in the atmosphere of more than 100 years. In addition, a
molecule of nitrous oxide has more than 300 times the heat-trapping
effect in the atmosphere as a molecule of carbon dioxide.

In
soils, the production of nitrous oxide through microbial activity is a
natural process. By applying large amounts of fertilizer, however,
humans have greatly increased the amount of nitrous oxide in soils. This
is particularly true when nitrogen fertilizer is added in larger
amounts than the crop needs, and when it is applied at times or in ways
that make it difficult for the crop to get the full benefit.

"Improving
the efficiency of nitrogen use for field crop agriculture holds great
promise for helping mitigate climate change," Robertson says.

The
nitrous oxide greenhouse gas reduction methodology, which is a way for
farmers to participate in existing and emerging carbon markets, recently
was approved by the American Carbon Registry and is in its final stages
of validation by the Verified Carbon Standard—two carbon market
standards that operate worldwide.

When
farmers reduce their nitrogen fertilizer use, they can use the
methodology as a means of generating carbon credits. These credits can
be traded in carbon markets for financial payments.

The
scientific underpinning for the methodology rests on decades of
research Robertson and colleagues have conducted at the KBS LTER site.

Scientists at the KBS LTER site research agriculture and climate change. Credit: Kurt Stepnitz

The
idea of the methodology is to offer ways of using less fertilizer to
produce crops. But if farmers apply less fertilizer, will their crop
production take a hit?

"Carbon
credits provide an incentive to apply fertilizer more precisely, not to
reduce yields," says Robertson. "If yields were reduced significantly,
the climate effect would be nil because a farmer somewhere else would
have to use more nitrogen to make up the yield loss, thereby generating
more nitrous oxide."

The
new methodology developed at NSF's KBS LTER site was successfully used
by a Michigan farmer in Tuscola County as part of a proof-of-concept
project.

"A
major value of the approach is that it is straightforward to understand
and implement," says KBS LTER scientist Neville Millar, who co-led
development of the methodology.

In addition to providing an economic incentive, the methodology is a tool farmers can apply to enhance their land stewardship.

"The
same strategies that farmers can use to minimize nitrous oxide loss
will act to reduce the loss of nitrate to groundwater and loss of other
forms of nitrogen to the atmosphere," says Millar.

Adam
Diamant, technical executive at the Electric Power Research Institute
and a co-developer of the methodology, says the new approach resulted in
a "quadruple win: for farmers, for industrial organizations that may be
required to reduce their greenhouse gas emissions, for the atmosphere
and for water quality from the upper Midwest all the way to the Gulf of
Mexico."

Adds Robertson: "We're in uncharted territory with a growing global human population and unprecedented environmental change.

"Performing
the research that links environmental benefits to environmental
markets, without compromising crop yields, is crucial for feeding more
people while sustaining Earth's ecosystems."